The present invention relates to high performance aromatic heterocyclic polymer compositions.
Rigid-rod benzobisazole polymers have excellent thermal and oxidative stability and solvent resistance. They exhibit superior tensile strength and modulus when fabricated from the liquid crystalline state into film and fiber. Although their mechanical properties (tensile strength and modulus) are far superior to the state-of-the-art, they lack the required compressive strength to be utilized in organic structural composites. We have prepared new benzobisazole polymer compositions based on extended-rod conformations that provide a mechanism for improved compressive properties.
In accordance with the present invention there are provided benzobisazole polymers having repeating units of the formula 
wherein Z is 
wherein X is xe2x80x94Sxe2x80x94, xe2x80x94Oxe2x80x94 or xe2x80x94NHxe2x80x94.